Stamping and forming



Jan. 2, 1945. Q BURGESS 2,366,487

STAMPING AND FORMING Filed June 12 1943 2 Sheets-Sheet l FlG.l.

231? 20 REMELTING 6 STATION 2| a -& STRIPPING 2 snmou PRESSURE T ROLLERg s'nmon 22/ 2 24b 3 I9 23 v a! RE-CASTING E SHEET METAL STATION WORKBLANKS 2 x 25 RECAST MATRIX BLANKS j g r 23 g EMPTY mes OR on: PLATES JRE-ASSEMBLY STATION FIG.2.

INVENTOR.

CHARLES E.BURGESS BY ATTORNEY Jail. 2, 1945. c BURGESS 2,366,487

STAMPING AND FORMING Filed June 12, 1943 2 SheecsSheet 2 FIG. 3.

WWW/WWW FIG. 6.

I N VEN TOR.

CHARLES E. BURGESS ATTORNEY Patented Jan. 2, i945 UNITED STATES PATENTmm:

2,366,487 STAMPING AND FORMING CharlesEdward Burgess, Trenton, N. J.

Application June 12, 1943, Serial No. 490,606

' 9 Claims. (01.113-51) This invention relates to a method of stamp--ing as well as to a method of compound stamping made female dies. vThis invention proposes the use of a matrix of a non-resilientlydeformable or malleable material as a matrix and a suitable metal alloyof suitable characteristics is herein proposed for that purpose. It isamong the objects of this invention not onlyto avoid the necessityofmaking the female dies but to obtain more sharply defined stamped andformed sheet metal products, and to avoid certain manufacturinglimitations inherent to the older method of using a rubber matrix.

-According to one embodiment of. this invention, an assembly of a maledie structure or die plate, a sheet metal work blank, and anon-resiliently deformable matrix material is subjectedto the pressureof pressure rollers. Thus the deformable material is caused to stamp outblanks from the sheet metal, or to form a Work blank over a die, or ifthe die be accordingly constructed as a compound stamping and formingdie to perform both steps, namely the blanking and forming in oneoperation.

Features'of this invention relate to the use of loy of specialcharacteristics. These features also have to do with the conditionsunder which the.

material is to be used, and the ways and means of stripping the deformedmaterial from the assembly.

Accordingto one s v outed by means of a suitable metal alloy serving asa matrix, and while maintaining it at a ternperature corresponding toits optimum point of malleability or plasticity, but not high enough toaffect adversely the metallurgical structure of the material of the dieand/or of the work.

According to another feature the matrix material is a metallic substanceor alloywhich if cooled within the temperature operating rangesof thisprocess, will expand rather than shrink; in other Words, so to speak,has a negative factor of thermal expansion. 4

feature, the operation is exe- A material having optimum malleabilitycharacteristics in an elevated temperature range, but which willrelatively expand in a lower temperature range, is selected according tothis feature,

' so that the stripping of the material may be facilitated after thenon-resilient deformation of w the matrix has taken place as a result ofthe pressure or rolling operation.

l bodily stripped therefrom, and it further requires meltingtemperature.

Still another feature requires that the metallic deformable matrixmaterial or alloy be melted directly off the .work assembly'instcad ofbeing first that the thus molten material be directly recast into newmatrix blanks for reuse in th process.

Consequently the matrix material in that instance should not only havesuitable malleability characteristics, but should moreover have a lowenough melting point so that the metallurgical structure of neither thedie nor the sheet metal work piec should be adversely affected by the Aspecial advantage resulting from the practice of this feature lies inthe fact that it allows the performance of combined stamping and formingoperations in one pressure operation as will be explained more fullyhereinafter.

The invention possesses other objects and features of advantage, some ofwhich with the foregoing will be set forth in the following description.In the following description and in the claims, parts will be identifiedby specific names for convenience, but they are intended tobe as genericin their applicationto similar parts as the art will permit. In theaccompanying drawings there has been illustrated the best embodiment ofthe invention known to me, but such embodi ment isto be regarded astypical only of many possible embodiments, and the invention is not tobe limited thereto.

The novel features considered characteristic of my invention are setforth with particularity in the appended claims. The invention itself,however, both as to its organization and its method of operation,together withadditional objects and the matrix material off the workassembly prior to stripping the sheet metal work parts off the dies.

Figs. 3 to 6 illustrate the production of a relatively more complicatedpart by way of a combined stamping and forming operation in the manneraccording to this invention.

To illustrate a simple stamping operation as performed according to thisinvention with the aid of a non-resiliently deformable matrix materialor metal alloy, Fig. 1 shows a pair of pres-- sure rollers 10 and Hbetween which passes a work assembly comprising a die plat l2havingmounted thereon or integral therewith' thestamping dies l3, asheet metal strip 14 repre senting the work blank into which holes areto be stamped by the dies I3, and a matrix I of non-resilientlydeformable material, that is a material capable of assuming a permanentdeformation under pressure, such as a suitable metal alloy havingadequate plasticity or malleability, and optionally also having suitabletemperature characteristics such as certain thermal expansion orcontraction factors and a certain melting point.

A number of such materials includes metal alloys of which the bismuthcontaining alloys are an example, and such as are exemplified by thekind of materials known as Cerro base metal and Cerrobend and otherwiseproportioned similar alloys. Cerro base metal and Cerrobend are productsof the Cerro de Pasco Copper Corporation of New York city. They arebismuth and lead containing alloys of which Cerrobend for instance isrepresented by the following average composition:

Cadmium Approx 10.0 Tin do 13.0 Bismuth- 40.0-49.0 Lead 28.0-32.0

It is among the advantages of the bismuth alloys that they have arelatively low melting point, allowing the alloy to be melted off thestamped or formed article without affecting the properties of thearticles formed. Furthermore, the malleability and the flowability ofsuch alloys compare with that of lead when heated or chilled. Andfurthermore, with such alloys substantially no change involume isexperienced on solidification.

The die plate [2 is shown to be supported or guided fore and aft thepressure rollers by guide members l5 and i6. According to Fig. 1 thework assembly as above defined has partly passed through the pressureroller device, so that the forward portion of the assembly shows thedeformable forward portion of the matrix as having embedded in it thepunched out metal portions I! while the punched portion of the metalstrip I4 is being shown forced down over the stamping dies l3 as at M Inthe practice of the invention as diagrammatically represented in theembodiment of Fig. 1, one or more of the following operating conditionsor requirements may be present:

(a) The matrix material is a metal alloy strip or blank of suitabledimensions and of suflicient nature of the sheet metal work and of thedies. The use of this matrix material would require preheating ittogether with the other component parts of the work assembly, that is,together with the work blank and with the dies, to a suitable degree oftemperature and substantially maintaining that temperature Whilesubjecting the work assembly to the operating pressure between thepressure rollers whereby the stamping and/or forming in the workassembly is effected. Furthermore, if the matrix material is of the kindthat expands with rising temperature, care must be taken to remove thematrix from the assembly while hot: Thereupon the stamped or formed workcan be stripped from the dies on the die plate, and the deformed matrixmaterial can be reconditioned, for instance by remelting,vfor reuse inthe process.

(0) The matrix material operates under conditions similar to thosedescribed under (b), but has a factor of thermal expansion according towhich it will expand with a lowering of temperature. A material of thisnature will facilitate removing the deformed matrix from the workassembly since the elevated temperature necessary for the pressureoperation need not be maintained.

(d) The matrix material operates under conditions similar to'thosedescribed under (b) or (c), with the addition that the material has amelting point of such order that the material can be melted directly offthe work assembly instead of being bodily stripped or forced therefrom.Respective operating temperatures under such conditions may thereforesuitably be placed at about 150 F. for attaining the optimum ofmalleability or plasticity, and at about 300 F. for remelting thedeformed matrix material for the work assembly.

The manufacturing process involving the conditions specified under (11)is more fully illustrated in the flowsheet-like diagram of Fig. 2, andis'described as follows:

In an assembly station [8 the die plate l2 with its dies l3, the sheetmetal blank or work blank l4, and the matrix I5, are composed to formwhat is herein termed the work assembly unit. The thus-composed assemblymoves as indicated by the line l9 to a heating station l9 where theassembly is brought up to the temperature at which the matrix materialor alloy exhibits substantially its optimum of malleability orplasticity. The thus heat conditioned Work assembly unit passes to andthrough a pressure roller device 20 whereby concentrated and relativelyhigh pressure is caused to traverse over the length of the assemblyunit, thereby stampin the work blank as in natural malleability orplasticity to permit its the manner shown in Fig. 1 due to thenon-resilient deformation of the matrix. This pressure operation may beused to perform a plain stamping or a plain forming, or a combinedstamping and forming operation, an example of which latter is givenfurther below (see Figs. 3 to 6).

While the work assembly unit passes through the pressure roller device20 its temperature is kept up by some supplementary heating means, forinstance, by means of heated pressure rollers 20 and 20 The assemblyunit, including the now deformed matrix leaving the pressure rollerdevice, is received by a 'remelting station 2| in which the assembly isheated to a temperature at which the matrix material alone will melt offthe rest of the assembly, thus leaving the die plate and the dies freefor the work, that is the stamped or formed article, to be strippedtherefrom.

The molten matrix material is collected in the station 2| and in itsmolten state it is passed on .as indicated by line 22 to a recastingstation 23 where it is cast to form new matrix blanks which, asindicated by the line 23*, are sent to the assembly station l8 for reusein the process. At the same time the die plate with the stamped orformed sheet metal work thereon is passed to a stripping station 24where the work is stripped off the dies and removed from the processcycle as indicated by the line 24 From-the strippin station 24 the emptydie plates or dies are passed on to the assembly station l8 as indicatedby the line 24 The recast matrix material or matrix blanks from therecasting station 23 and the empty die plates from the stripping station24 as well a newly introduced work sheet blanks as designated by theline 25 enter into and meet in the assembly station l8 where they arecomposed to make new work assembly units to enter the process anew asindicated by the line l9 by way of entering the heating station 9*.

In Figs. 3 to 6 the manufacturing process of this invention, and morespecifically the one 11- lustrated in the cycle shown in Fig. 2, isshown to be applied to produce a more complicated article produced by acombined stamping and forming pressure operation. The article 21 (seeFig. 6) to be produced comprises a fiat body portion 28 having a hole 29and ,a flang'e or skirt portion 30 struck marginally at right anglesfrom the .body portion 28, forming a rounded corner portion 30 Inaddition, the flange portion 30 is shown to be provided with a row ofholes 3| of relatively small diameter. This example of a stamped andformed sheet metal product is being presented in view of the fact thatthe holes 3| could not be produced in such a pressure operation by meansof a matrix of the known resilient kind, and it is also presented inorder to demonstrate that with the sharper demarcation made possible bythe use of the novel non-resiliently deformable matrix material, holesof relatively small diameter can be stamped out of a sheet metal blank,whereas the effect of the known resiliently deformable material orrubber matrix was limited to the stamping out of relatively largerdiameter holes.

Accordingly Fig. 3 shows a die plate 32 having provided on it incombination a horse-shoe shaped stamping die 33 and a forming die 34having a rounded corner portion 34 surrounded by the stamping die 33, ahole 33 shown to be provided in the forming die 34. In order to simplifymatters the die plate 32 and the dies 33 and 34 are shown as oneintegral part.

In Fig. 4 the dies are assembled with a sheet metal work blank 35 and amatrix blank 36, this assembly to be passed through a pressure rollerdevice under the conditions described in conjunction with Fig. 2.

Fig. shows the result of the pressure operation,-namely the fact thatthe matrix material distributing itself under pressure into theaccessible places of the die arrangement has sheared off or stamped outa blank along the cutting line 31 of the stamping die 33, leaving excess:sheet material 38 on top of the stamping die 33; furthermore the factthat a portion equivalent to the diameter of the hole 33 in the formingdie has been stamped out of the sheet metal blank; further that aportion of the matrix material being plastically deformed under thepressure has been displaced into the space between the stamping orshearing die 33 and the forming die 34, thereby forming the flangeportion 30 upon the body portion 28 of the sheet metal article 21, bybending the flange portion 30 over the rounded corner portion 34 of theforming die 34; and finally that the matrix material by virtue of itadequate plasticity and because of the high specific roller pressureemployed, has forced itself through passages 39 provided in the formingdie 33 and extending in a direction at an angleto the direction of thepressure force applied, thereby stamping out the holes 3| of the article21 as substantiated by the showing of the stamped out slugs of sheetmetal 40.

Each of the horizontal passages 39 provided in the forming dieterminates in a downward opening or downward passage 4| for receivingand discharging the stamped out slugs 40.

After the combined stamping and forming operation in this instance hasbeen completed according to Fig. 5, the work assembly will; is subjectedtoa temperature at which the matrix material is melted oif the assembly,and especially melted out of the passages 39 and 40, so that the stampedand formed sheet metal article can be stripped from the die.

I claim:

1. The method of producing articles from sheet metal, which comprisesconfining a sheet metal work blank between a die member and a matrixmember of a metal alloy permanently deformable under pressure, andapplying to the assembly of die member, sheet metal and matrix member alocally concentrated rolling pressure force eifective to progressivelydeform the matrix material at the rate at which the rolling pressureprogresses over the assembly and thereby to cut an article from saidblank.

2. The method according to claim 1, in which the article is being cut aswell as formed by the co-action of said die member and said matrixmaterial.

3. The method according to claim 1, in which the matrix material isheated to a temperature at which the material shows substantially anoptimum degree of plasticity and is subjected to said pressure operationat substantially that temperature, said temperature being below thatwhich might adversely affect the metallurgical structure of the workblank or of the die member and of the Work blank.

4. The method according to claim 1, in which the assembly of said workblank, die member, and matrix member following the pressure operation issubjected to heating whereby matrix material is melted directly off theremainder of the assembly, the melting temperature of the material ofsaid matrix member being below any that would adversely affect themetallurgical structure of the die member and of the work blank.

5. The method according to claim 1, in which the matrix material isheated to a temperature at which the material shows substantially anoptimum degree of plasticity and in which the material is selected tohave a negative coeflicient of expansion, causing the material tocontract due to heating effects.

6. The method according to claim 1, in which a matrix material alloy isselected, containing a substantial proportion of bismuth.

at which the material shows a suificient degree of plasticity, and issubjected to said pressure operation at substantially that temperature,in which the deformed matrix material is melted directly 7. The methodaccording to claim 1, in which" the matrix material is brought to atemperature off th remainder of the assembly at a. temperature belowthat which adversely aflects the metallurgical structure of the workblankand of the die member, and in which said material in' the thusmolten state is recast in the thus molten state to form matrix blanksfor reuse in the process.

8. The method according to claim 1, in which a matrix material alloy isselected havingv an adequate degree of plasticity at about 150 F., and amelting point of about 300 F.

9. The method according to claim 1, in which a matrix material alloy isselected having a melting point of about 300 F., and having adequateplasticity at intermediate temperatures.

CHARLES EDWARD BURGESS.

